Avoid redefining IsMsgHandled by making all Win message handlers safe

There were two sets of message map macros, one with IsMsgHandled as a
function, one with it as a macro. If combined in some translation unit
that could cause compilation problems, and it did in some Opera builds.

This patch changes the code so that there is only one implementation
of the macros and it's the "safe" one, where "safe" means that it
can handle that the underlying object is deleted inside a message
handler without crashing.

Cq-Include-Trybots: luci.chromium.try:android_optional_gpu_tests_rel;luci.chromium.try:linux_optional_gpu_tests_rel;luci.chromium.try:mac_optional_gpu_tests_rel;luci.chromium.try:win_optional_gpu_tests_rel;master.tryserver.chromium.win:win_optional_gpu_tests_rel
Change-Id: I2f039d8d93a539c8322caa664e642956c5d6d372
Reviewed-on: https://chromium-review.googlesource.com/995896
Reviewed-by: Scott Violet <sky@chromium.org>
Commit-Queue: Scott Violet <sky@chromium.org>
Cr-Commit-Position: refs/heads/master@{#550711}
10 files changed